Pinholes In Shuttle Wings Overlooked

Probe: Small Breaches Hinted At Larger Problems

April 16, 2003|By Tribune Newspapers

HOUSTON — The space shuttle Columbia's wings and fuel tank were riddled with a virtual minefield of holes and cracks, a flaw that was largely overlooked by NASA but almost certainly contributed to the craft's demise, investigators said Tuesday.

According to interviews and internal documents, the National Aeronautics and Space Administration has known since the early 1990s that its fleet of aging shuttles was pocked with pinholes. What it failed to grasp -- and could not see -- was the danger beneath the holes.

A review of the pieces that make up the orbiters' wings has revealed that many of those pinholes were akin to the hole at the top of a volcano. They didn't look like much on the surface, but they were openings to far more extensive breaches, said U.S. Navy Rear Adm. Stephen Turcotte, a member of the independent Columbia Accident Investigation Board.

Those underlying breaches likely have eroded the structural integrity of the space shuttles' wings -- a problem that was particularly acute in the case of the Columbia, which was on its 28th mission when it ripped apart Feb. 1, killing its seven-member crew.

Investigators especially want to know whether the holes, metal corrosion apparently caused by oxygen, damaged Columbia's "T-seals" -- the boomerang-shaped carbon braces that held together and sealed the leading edge of the shuttle's wings.

U.S. Department of Defense radar images show that a piece of the Columbia broke off and drifted away during the second day of the ill-fated mission. Investigators said Tuesday they now suspect that the piece was either one of the T-seals or a fragment of one. If so, that would have created enough of a hole for superheated gas, known as "plasma," to penetrate the craft and ultimately bring it down, investigators said.

Currently, NASA's pre-flight inspection routine consists of little more than visual scans of wing surfaces with the aid of a magnifying glass -- examinations that are not sophisticated enough to reveal internal damage, investigators said.